1. Field of the Invention
This invention generally relates to a front derailleur chain detachment prevention member. More specifically, the present invention relates to a front derailleur chain detachment prevention member that is installable on the transmission device of a bicycle.
2. Background Information
Bicycling is becoming an increasingly more popular form of recreation as well as a means of transportation. Moreover, bicycling has become a very popular competitive sport for both amateurs and professionals. Whether the bicycle is used for recreation, transportation or competition, the bicycle industry is constantly improving the various components of the bicycle. One component that has been extensively redesigned is the bicycle drive train.
Bicycles, and particularly sport type bicycles, use chain driven types of drive trains with a front transmission device including a front derailleur and front chain wheel with two or three sprockets, and a rear transmission device including a rear derailleur and multi-stage gears with seven to ten sprockets. In the front derailleur of this type of drive train, the chain may not engage the sprocket on the small diameter side so as to detach on the inside when downshifting as the chain is guided from the sprocket on the large diameter side to the sprocket on the small diameter side. Conventional front derailleurs are known to have a front derailleur chain detachment prevention member for preventing the chain from detaching on the inside (for example, refer to Japanese Laid-Open Patent No. 55-10427).
A conventional front derailleur chain detachment prevention member is disposed on the inside of an inner plate of a chain guide for a front derailleur, and is installed on the link shaft of a linkage mechanism. Specifically, two mounting parts are disposed on the inside of the inner plate, and both of the mounting parts and the inner plate are installed together on the link shaft of a linkage mechanism so as to reciprocate between a top shift position and a low shift position.
The front derailleur chain detachment prevention member must be replaced according to the number of teeth of the sprocket. That is, when there is a large difference in the number of gear teeth between the large diameter sprocket and the small diameter sprocket, a member with a large dimension in the diameter direction must be installed to prevent chain detachment. In a conventional structure, however, the entire front derailleur must be disassembled when intending to remove the front derailleur chain detachment prevention member since the mounting parts are installed on the link shaft of a linkage mechanism. Therefore, the front derailleur chain detachment prevention member can not be removed easily.
Furthermore, in a conventional structure, the front derailleur chain detachment prevention member may come into contact with the small diameter sprocket when the front derailleur chain detachment prevention member is disposed at the high-speed position opposite the large diameter sprocket. When the front derailleur chain detachment prevention member comes into contact with the sprocket, the small diameter sprocket and the front derailleur chain detachment prevention member are subject to wear, and a contact-induced abnormal noise is generated.
In view of the above, it will be apparent to those skilled in the art from this disclosure that there exists a need for an improved front derailleur chain detachment prevention member. This invention addresses this need in the art as well as other needs, which will become apparent to those skilled in the art from this disclosure.